Bacterial biodegradation of Benzo[a]pyrene

1. Bacterial biodegradation of Benzo[a]pyrene Min Schrader & Alexis Brandow Δ

2. Polyaromatic Hydrocarbons (PAHs)

3. Sources Natural vs. Anthropogenic Pictures from various sources

4. Path of PAHs • Airborne PAHs precipitate to the ground. • Carried by runoff into surface waters. • Consumed by aquatic life.

5. Process of bioaccumulation. 1 µg 10 µg 100 µg 1000 µg • No known, or studied, risk to the seafood. • Larger animals store all of the accumulated PAHs in their fatty tissues. • Shoreline spills contaminate more than off-shore spills.

6. Epoxidation & Toxicity Can occur in environment or inside human body. Complete process will: Increases polarity, increases mobility, & easily excreted. Increased mobility can either increase or decrease reactivity. More reactive epoxidation steps increase carcinogenic potential. Incomplete process can: Increase polarity, decrease mobility, and decrease normal excretion rate. Epoxidases: epoxidation enzymes in some species.

7. Volatility & Remediation • Volatile compounds. • PAHs size & evaporation trends. • Water turbulence, dispersion, & sedimentation. • Efficient remediation must be self-sustaining and on-site. • Avoid potential adverse effects of introducing new substances.

8. Natural Remediation • Environment equipped to remediate some PAHs in some quantities. • Capable of handling some anthropogenic excess of smaller PAHs • With time, natural processes heal the ecosystem. • Some can be aided. • Weathering processes.

9. Anthropogenic Remediation • Off-site Remediation • “Dig up and transport” to process. • Exorbitant cost, time, and labor. • Only used for the most toxic and immediate concerns. • In-situ remediation • Applying “remedy” on-site. • Cheaper, less reliance on machine and human labor. • Some processes can be self-sustaining.

10. In-Situ Remediation • Photo-degradation (flash chromatography and photolysis). • Thermal enhancements. • Phytoremediation. • Microbial activity.

11. Benzo[a]pyrene (B[a]P) Less volatile. Larger, heavier, bioaccumulative Known cause of cancer, heritable genetic damages, impaired fertility, and fetal harm Known toxin to larger land & aquatic organisms. B[a]p and B[e]p – Essentially the same. Molecular formula C20H12 Formula weight of 252.31 grams per mole. B[e]p is only known for carcinogenic and aquatic effects.

12. Question & Hypotheses • Identify a benign, site-specific bacteria guild. • Efficient, in situ treatment. • Decompose benzo[a]pyrene (B[a]p) into less toxic products. • Cultured, site-specific guild bacteria. • Bacteria guilds composed of diverse group of bacteria. • Each species crucial for a particular step of the reaction. • Cultured, site-exotic guild bacteria. • No cultured bacteria guild are successful.

13. Persistance • B[a]p persists in the environment for 84 years. • Small PAHs like naphthalene last for 8 months. • Biodegradation - decomposition of compounds by plants, animals, & microbes. • Dominant, natural remediation. • Biodegredation better than “clean up”. • Hydrocarbons are energy for 90 species of bacteria.

14. Spring Quarter Plans • Site tests and lab experiments. • Choose specific contaminated site. • Take samples to determine the most contaminated one-mile square area in most urgent need of bioremediation. • Test new samples from area. • Take at least three samples from each sample site • Ideal to use native bacteria. • Test whether “exotic” bacteria affects adversely.

15. Needs & Future Questions • Determine a supplier, if necessary. • Obtain permits, or other permissions. • Time restrictions on use of site vs. length of lab study? • Compare other remediation methods, times, and costs to our method. • Success with B[a]p work on other PAHs?

16. References: • 1.      Awata H.; Bates S.; Knuab D. & Popelka R.. Environmental Organic Chemistry. 1998, Spring. • 2.      American Petroleum Institute Environmental, Health and Safety Mission and Guiding Principles. (November 1996). February 2002, http://api-ec.api.org/environ/index.cfm?bitmask=001003000000000000 • 3.      Rodgers R. P.; Lazar A. C.; Reilly P. T. A.; Whitten W. B.& Ramsey J. M.. Analytic Chemistry. 2000, 5040-5046. • 4.      Jim Neitzel. Evergreen State College, Olympia, WA, January 2002; interview. • 5.      Brad Jackson. EPA, Renton, WA, January 2002; e-mail. • 6.      Cometabolic Bioventing Field Test Conducted at Dover Air Force Base: 2000; U.S. Environmental Protection Agency. National Risk Management Research Laboratory. • 7.      In Situ Remediation—Status Reports. (January 1996). February 2002, http://www.epa.gov/tio/products/newsltrs/gwc/gwcabiot.htm • 8.      EPA Grows Solutions to Clean-Up Problems at Toxic Sites. (March 2001). February 2002, http://www.epa.gov/epahome/other_031501.htm • 9.      A Citizen’s Guide to Phytoremdeiation. (n.d.). February 2002, from http://www.epa.gov/swertiol/download/citizens/citphyto.pdf • 10.  New Technology Transfer Products Coming Your Way. (January 2001). February 2002, http://www.epa.gov/ttbnrmrl/ca.html • 11.  Lahlou M; Harms H.; Springael D. & Ortega-Calvo J-J. Environmental Science Technology 2000, 34, 3694-3656. • 12.  Search on “benzopyrene” at http://www.chemexper.com

17.  Acknowledgments: • Rachel Jameton, TESC Chemistry faculty, Matter and Motion • Melissa Barnhart, TESC Chemistry tutor, Matter and Motion • Aaron Barnes, TESC Science Instruction Technician • Carolyn Mayer, PSC